A typical lighting fixture may be designed to emit light that has a particular Correlated Color Temperature (CCT). For example, an LED light fixture may emit a warm white light (e.g. 2700-3000 K), a cool white light (e.g., 5000-6000 K) or a light with a CCT between warm and cool white lights. In some cases, a light fixture may be tuned to emit a light with a desired CCT. White color tuning may be performed to produce a light with a desired CCT. For example, white color tuning is commonly accomplished by using a combination of warm white light and cool white light, resulting in a combined light with a combined CCT that is a combination of the CCT of the warm white light and the CCT of the cool white light.
Sometimes, LEDs that emit a light with different particular color, such as Red, Green, Amber and Blue, are used with LEDs that emit warm white light and cool white light to move the combined CCT from one point of the black body curve to another. On a chromaticity chart, the combined CCT of the light resulting from such a combination of lights sits on a straight line joining a CCT of the warm white light and a CCT of the cool white light. In general, achieving a specific lumen output from such a combination requires twice the number of LEDs than needed to produce just a warm white light or just a cool white light. Further, the combined white light generally moves away from the black-body radiation curve as the combined CCT moves toward halfway between the warm and cool white lights. Achieving white light tuning cost effectively and reliably while keeping the CCT of the light relatively close to the black-body radiation curve can be challenging. Thus, a solution that enables white light tuning cost effectively and accurately to produce light that is relatively close to the black-body radiation curve is desirable.
The drawings illustrate only example embodiments and are therefore not to be considered limiting in scope. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Additionally, certain dimensions or placements may be exaggerated to help visually convey such principles. In the drawings, reference numerals designate like or corresponding, but not necessarily identical, elements.